Dozens killed as UAE-backed southern separatists seize all government military camps in Yemen's Aden

Deadly fighting raging in Aden since Wednesday is pitting unionist forces loyal to the internationally recognised government against a force that supports it but is dominated by fighters seeking renewed independence for the south.

The force, known as the Security Belt, took control of all military camps in the city belonging to the internationally-recognised government, an official said.

They also took over the home of Interior Minister Ahmed al-Mayssari, which he had already vacated, officials said.

Yemeni officials said at least 45 people, both combatants and civilians, died in clashes overnight at the Fourth Brigade camp. Another five civilians were killed in the surrounding Dar Saad neighborhood.

Fierce clashes were also taking place in several other parts of the city.

The latest fighting raises the death toll to 70 people killed in in Aden this week.

UAE Foreign Minister Abdullah bin Zayed Al-Nahyan expressed "deep concern" on Saturday over the violence in Aden and called for a "de-escalation".

"Sheikh Abdullah called for a responsible and serious dialogue to end the differences and work on unity in this delicate phase while maintaining security and stability." the official Emirati news agency WAM reported.

He said the UAE was "exerting all efforts to calm and de-escalate the situation in Aden", saying the two camps should focus their efforts on fighting the Houthis not each other.

Sheikh Abdullah also called on the UN envoy to Yemen Martin Griffiths "to make all possible efforts to end the escalation in Aden", the statement added.

Southern Yemen was an independent state until 1990 and the north is widely perceived to have imposed unification by force.

The Security Belt is a force trained by the United Arab Emirates, a key partner in a Saudi-led military coalition which intervened in Yemen more than four years ago to prop up Hadi's government in the face of an uprising by Iran-aligned Shia Houthi rebels.

Read more: Yemen in Focus: War takes a new turn as Saudi, UAE allies pursue disparate agendas

The Houthis control large parts of northern and western Yemen, including the capital Sanaa.

On Thursday, Hadi's government urged Saudi Arabia and the UAE to put pressure on the Security Belt to avoid a military escalation in Aden.

Fighting in the city flared on Wednesday after two members of the Security Belt were killed in clashes with other loyalist forces after the funeral of police personnel killed in the city last week, according to security officials.

A missile and drone attack by Houthi rebels on a Security Belt training camp just outside Aden last week killed 49 people, many of them newly graduated cadets.

The UN human rights office this week accused the Security Belt force of "reportedly carrying out and enabling retaliatory attacks against civilians" from northern Yemen.

On Wednesday, the UN envoy to Yemen Martin Griffiths wrote on Twitter that he was "alarmed by the military escalations in Aden".

Clashes between the two sides have left at least 18 dead since Wednesday and scores of wounded, medics and security sources have said.

On Friday, Doctors Without Borders (MSF) tweeted that it had treated 75 people in one of its hospitals in Aden since Thursday night.